The present invention relates to a softener composition.

Most of the commercially available merchandise as a softener composition for fibers are compositions comprising a quaternary ammonium salt containing two long-chain alkyl groups in one molecule and being typified by a di(long-chain alkyl) dimethyl ammonium chloride.

However, the quaternary ammonium salt described above suffers from the problem that, when residues thereof after a treatment is discharged into the environment such as a river, most of them are accumulated without biodegradation.

As an improved product against the above-mentioned problem, N-methyl-N,N-bis(long-chain alkanoyl oxyethyl)-N-(2-hydroxyethyl) ammonium methyl sulfate, N,N-dimethyl-N,N-bis(alkanoyloxyethyl) ammonium chloride or the like is commercially available. Although the biodegradability of the improved product is improved as compared with that of the quaternary ammonium salt described above, the improved product cannot be said to be a base for sufficiently satisfying a softening effect.

On the one hand, a laundering machine being a water-saving type becomes popular in recent years. That is, a laundering and softening treatment are carried out with a smaller amount of water than that the conventional machine needs. In the case of a softening treatment under such a condition, a softener into which the above-described quaternary ammonium salt is blended, as it is, suffers from the problem that the softening effect cannot be sufficiently obtained.

On the other hand, it is desirable from the viewpoint of a resource-, energy- or space- saving that the softener is highly concentrated. However, when the quaternary ammonium salt described above is blended, as it is, at a high concentration, there is the problem of a higher viss, gelation or separation during a storage.

As the prior art, JP-A 6-228875 discloses a softener composition comprising a di-long-chain quaternary ammonium salt and a di-long-chain amine in the ratio of from 99/1 to 85/15 and JP-A 5-195432 discloses an ester amide-based quaternary salt or a tertiary amine/alkanol amide neutralized salt. However, the creaky feeling of clothes and so on cannot be effaced by any one of the prior arts described above.

EP-A-0 634 475 relates to low viscosity, flowable aqueous dispersions containing high concentrations of fabric softeners. The compositions comprise an inorganic or organic acid salt of a fabric softening compound which is an amido or ester tertiary amine and a biodegradable fatty ester quaternary ammonium compound.

Accordingly, the object of the present invention is to provide a softener composition which establishes a favorable softening effect even though treated with a small amount of water, which establishes a little or little creaky felling, which has a high biodegradability and which further shows an excellent storage stability even though blended at a high concentration.

The present inventors have found that the problem described above can be solved by using a cationic surfactant having at least two selected from long-chain alkyl and alkenyl groups in combination with a specific amine or a salt thereof. And then, the present inventors have completed the present invention.

That is, the present invention provides the softener composition which comprises a component (A) containing an amine represented by the following formula (I), a salt thereof or a mixture of the same and a component (B) containing a compound represented by the following formula (II-2) as the essential component and optionally containing at least one of the compounds represented by the formulae (II-1) and (II-3), wherein the ratio of the component (A) to the component (B), namely (A)/(B), by weight is from 2/8 to 8/2: wherein R¹ and R² are the same or different and each of R¹ and R² represents a hydrogen atom, a C_1-3 alkyl group, - (C_mH_2mO)_p-H, -C_nH_2n-X-R³ or -C_qH_2q-Y-R³; m, n and q are the same or different and each of m, n and q represents an integer of 1 to 6; p represents a number selected from 1 to 10; R³ represents a linear or branched C_5-22 alkyl or alkenyl group; X represents -OCO- or -COO-; and Y represents -NHCO-, -CONH-, -O- or -CH₂-; provided that at least one of R¹ and R² is -C_nH_2n-X-R³ or -C_qH_2q-Y-R³; wherein R⁴ represents a C_1-3 alkyl group or -(C_mH_2mO)_p-H ; R⁵ represents a C_6-22 alkyl or alkenyl group, -C_nH_2n-X-R³ or -C_qH_2q-Y-R³; each of m, n, p, q, R³, X and Y has the same meaning as defined above; Z^- represents an anion; and one of the plural R⁴'s sand R⁵'s may be same as or different from another.

In the present invention, the content of the component (B) is 11 to 50 % by weight as compared with the softener composition, provided that is excluded the case where the component (A) is represented by the following formula (a-1) and the component (B) is represented by the following formula (b-1):

The component (A) in the present invention is preferably an amine represented by the formula (III), a salt thereof or a mixture of the same: wherein R¹ represents a hydrogen atom, a C_1-3 alkyl group, - (C_mH_2mO)_p-H, -C_nH_2n-X-R³ or -C_qH_2q-Y-R³; m, n and q are the same or different and each of m, n and q represents an integer of 1 to 6; p represents a number selected from 1 to 10; R³ represents a linear or branched C_5-22 alkyl or alkenyl group; X represents -OCO- or -COO-; Y represents -NHCO- or -CONH-; and R² represents -C_qH_2q-Y-R³.

The amine represented by the formula (I) or (III) is synthesized by acylation of an amino alcohol or diamino alcohol represented by the formula (IV) with a fatty acid or a lower alkyl ester thereof: wherein R¹' and R²' are the same or different and each of R¹' and R²' represents a hydrogen atom, a C_1-3 alkyl group, - (C_mH_2mO)_p-H or - C_qH_2q-NH₂; each of m, n, p and q has the same meaning as defined above; and at least one of R¹' and R²' is - (C_mH_2mO)_p-H or -C_qH_2q-NH₂. The degree of acylation in total is preferably 1.2 to 2.5 and more preferably 1.5 to 2.3. For example, the amino alcohol represented by the formula (IV) may be triethanolamine, N-methyldiethanolamine, N-methyl-N-(2-hydroxyethyl)propanediamine or N,N-di(2-hydroxyethyl) propanediamine or the like. The number of carbon atoms in an acyl moiety in the fatty acid or the lower alkyl ester thereof for use is preferably 6 to 22 and more preferably 8 to 18. For example, a fatty acid from a coconut, a tallow fatty acid, a hardened (or hydrogenated) tallow fatty acid, stearic acid from a palm, hardened stearic acid from a palm or a lower alkyl ester thereof is particularly preferable. Further, a fat and/or oil such as a coconut oil, a tallow, a hardened tallow, a palm-stearin and a hardened palm-stearin may be also used.

The salt of the amine can be synthesized in a usual manner by neutralization with an inorganic or organic acid such as hydrochloric acid (an aqueous solution of hydrogen chloride), sulfuric acid, phosphoric acid, glycolic acid, lactic acid, tartaric acid, citric acid and succinic acid.

The amine represented by the formula (I) or (III) is preferably represented by the formula (Ia), (Ib), (Ic) or (Id) and more preferably represented by the formula (Ic) or (Id): wherein R³ has the same meaning as defined above and R⁶ represents a methyl or hydroxyethyl group; wherein R³ has the same meaning as defined above; wherein each of R³ and R⁶ has the same meaning as defined above and i represents 2 or 3; wherein each of R³ and i has the same meaning as defined above.

The cationic surfactant used as the component (B) in the present invention contains a component represented by the formula (II-2) as the essential component and may further contain a component or components represented by the formula (II-1) and/or (II-3). The component (II-2) is preferably represented by the formula (IIa) or (IIb), in particular: wherein R⁴ represents a C_1-3 alkyl group or -(C_mH_2mO)_p-H ; R⁵ represents a C_6-22 alkyl or alkenyl group, -C_nH_2n-X-R³ or -C_qH_2q-Y-R³; each of m, n, p, R³, X and Y has the same meaning as defined above; Z^- represents an anion; and one of the plural R⁴'s and R⁵'s may be same as or different from another; wherein R³ has the same meaning as defined above; R⁷ represents a methyl or hydroxyethyl group; and Z₁^- represents a chloride ion or methyl sulfate ion; wherein each of R³, R⁷ and Z₁^- has the same meaning as defined above and r represents 2 or 3.

For example, the cationic surfactant represented by the formula (IIa) or (IIb) is synthesized by acylation of an amino alcohol such as triethanolamine, N-methyldiethanolamine, N-methyl-N-(2-hydroxyethyl)propanediamine and N,N-di(2-hydroxyethyl) propanediamine with a fatty acid or a lower alkyl ester thereof and further quaternarization of the resultant product with a quaternarizing agent such as methyl chloride (or chloromethane) and dimethyl sulfate. The degree of acylation in total is preferably 1.1 to 2.8 and more preferably 1.5 to 2.5. The fatty acid or the lower alkyl ester thereof for use is preferably the above-mentioned one.

Preferably, the present invention provides the softener composition wherein the component (B) is a cationic surfactant containing a component represented by the formula (II-5) as the essential component and optionally containing a component represented by the formula (II-4) or (II-6): wherein R⁴ represents a C_1-3 alkyl group or -(C_mH_2mO)_p-H; R⁵ represents a C_6-22 alkyl or alkenyl group or -C_nH_2n-X-R₃; each of m, n, p, R³ and X has the same meaning as defined above; Z^- represents an anion; and one of the plural R⁴'s and R⁵'s may be same as or different from another.

The ratio of the component (A) to the component (B), namely (A)/(B), by weight in the softener composition of the present invention is from 2/8 to 8/2, preferably 3/7 to 7/3 and particularly preferably 4/6 to 6/4. If (A)/(B) is less than 2/8, the softener composition shows an inferior storage stability, while (A)/(B) is more than 8/2, it shows an inferior softening effect.

The components (A) and (B) can be formed into the liquid softener composition of the present invention by dispersing them in a total amount of 3 to 50 % by weight in water. In this case, the components (A) and (B) may be mixed and then introduced into water or they may be introduced one after another into water. Alternatively, the respective components may be separately dispersed in water and then mixed.

The softener composition of the present invention has pH value of preferably 1.5 to 6.0 and more preferably 2.0 to 5.0 at 25 °C in view of a dispersibility and storage stability of the amine compound.

A higher alcohol or higher fatty acid can be added in order to further improve a softening performance. A lower alcohol such as ethanol and isopropanol, glycol or polyol as well as an ethylene oxide or propylene oxide adduct thereof can be added as a storage stabilizer. Furthermore, a usual nonionic surfactant, an inorganic salt, a pH adjuster, a hydrotropic agent, a perfume, a defoaming agent, a pigment and the like can be added if necessary.

As shown in Table 1, (A-1) to (A-5) as the component (A) and (B-1) to (B-5) as the component (B) were used. They were dispersed in water in amounts shown in Table 1 to prepare each of the softener compositions. This composition was evaluated for a softening effect and storage stability in the following manner. The results are shown in Table 1.

• ① A mixture of the components (A) and (B) was molten and added dropwise to water under stirring. Then, a 6 mol/L hydrochloric acid was further added thereto to adjust pH of the mixture to from 2 to 3, so that a dispersion having a solid content of 20 % by weight was prepared. As a comparative control sample, a dispersion of N-methyl-N,N-bis(tallow alkanoyloxyethyl)-N-(2-hydroxyethyl) ammonium methyl sulfate was prepared in the same manner as above.
• ② A treating method
  3 kg of commercially available cotton towels or 3 kg of jersey cloths made of acrylate fibers were laundered repeatedly 5 times with a commercially available detergent "Attack" (a registered trade mark, manufactured by Kao Corporation) in hard water of 3.5° DH in a laundering machine having its capacity of 30 liter. Then, 30 ml of the above dispersion were introduced thereinto and the resultant mixture was treated under stirring at 25 °C for 1 minute.
• ③ A method for evaluating a softening effect and feeling of touch of clothes
  The cloths treated in the method described above were air-dried at room temperature and then left in a constant temperature and humidity chamber at 25 °C under 65 %RH for 24 hours. These clothes were evaluated for a softening effect and feeling of touch. A cloth treated with N-methyl-N,N-bis(tallow alkanoyl oxyethyl)-N-(2-hydroxyethyl) ammonium methyl sulfate was used as the control for evaluation by the paired comparison test. The results are shown using the following criteria. For a feeling of touch of the clothes, "+" was assigned when the jersey cloth made of acrylate fibers was less creaky than the control and "-" was assigned when the jersey cloth was more creaky than the control.
  +2: Softer than the control or less creaky than the control.
  +1: Somewhat softer than the control or somewhat less creaky than the control.
  0: Equal in a softening effect to the control or equal in creaky feeling to the control.
  -1: Somewhat harder than the control or somewhat more creaky than the control.
  -2: Harder than the control or more creaky than the control.
• ④ A method for evaluating a storage stability
  The dispersion prepared in the method described above was calmly left in a constant temperature chamber at 30 °C for 1 month and then evaluated visually for the state of the dispersion using the following criteria.
  ○: Not changed after 1 month.
  ×: Separated or thickened after 1 month.

As shown in Table 1, only the component (A), only the component (B) or the components (A) and (B) were dispersed in water in amounts shown in Table 1. Then, they were evaluated for a softening effect, feeling of touch of clothes and storage stability in the same manner as in Example 1. The results are shown in Table 1.

As shown in Table 1, an ester linkage-free amine (C-1) was used in place of the component (A). The amine (C-1) was dispersed in water in an amount shown in Table 1. The resultant composition was evaluated for a softening effect, feeling of touch of clothes and storage stability in the same manner as in Example 1. The results are shown in Table 1.

As shown in Examples, the softener composition of the present invention shows both of a favorable softening effect and an excellent storage stability. On the other hand, the composition containing only the component (A) as shown in Comparative Example 1 or 2 or only the component (B) as shown in Comparative Example 3 or 4 cannot satisfy both of storage stability and softening effect. In addition, even if the composition contains both of the components (A) and (B), the composition cannot satisfy both of storage stability and softening effect, provided that the ratio of (A)/(B) by weight is not within the range of from 2/8 to 8/2, as shown in any one of Comparative Examples 5, 6 and 9 to 11, as well as only the component (A) or (B). Further, as shown in Comparative Example 7 or 8, the composition using the ester linkage-free amine in place of the component (A) cannot satisfy a storage stability.

Then, the composition in any one of Examples 3 to 5 and 9 to 12 is most preferable among the above-mentioned compositions.